The invention pertains to the method of forming a sealed caster and a sealed caster, per se, wherein resilient cover means are employed to seal relatively rotatable components from the entrance of foreign matter.
Caster wheels are utilized in a wide variety of applications wherein it is desired to mount structures upon wheels. Such casters are normally classified as fixed or nonswiveling types, or swiveling casters wherein the wheel-supporting leg structure is capable of rotation about a substantially vertical axis and the wheel axis is offset from the vertical axis wherein the caster automatically assumes a "trailing" relationship to the vertical swivel axis during motion.
It is not uncommon for apparatus supported upon casters to be utilized in a wide variety of ambient atmospheres and in many applications it is not uncommon for the atmosphere to which the caster is subjected to corrosively effect the caster bearing components, such as by water, heat, acids, vapors, and the like, and in those applications wherein the dust or dirt, or small particle content is high, such small particles of foreign matter often enter the caster bearings and movable parts, adhere to lubricating oils and greases, and accelerate the wear of the caster bearings and relatively moving components.
Casters have been produced of relatively noncorrodible materials, such as stainless steel, but such casters are very expensive and are usuable only in specialized locations wherein the cost is not a significant factor. Also, various types of casting and sealing means have been employed to minimize the entrance of foreign matter into caster bearing structure but such devices, in the past, have been expensive, relatively ineffective, and difficulty has been encountered in sealing the caster wheel axle structure effectively.
Also, in some applications, for instance in food service and hospital use, the ability of the caster to be cleaned and maintained in a hygienic condition is important, and previous caster constructions have created problems in this area in that their design resulted in a configuration difficult to clean and keep free of food particles.
Various attempts have been made to seal caster structure against foreign matter for purposes of improving the sanitation aspect, as well as improving bearing life, and my U.S. Pat. No. 3,399,421 discloses a "slip on" seal for casters toward this end.
Also, in many food handling applications, parts cleaning, and the like, casters are subjected to large amounts of water and moisture and unless the caster is constructed of relatively uncorrodible materials caster replacement on such devices is very high and maintenance costs excessive.